X11 connection error in Mac

Typically, I log into my remote server/cluster via "ssh -X" and from there launch R program for plotting. But it always shows an error as

unable to open connection to X11 display ''

after a while, when you want to call functions such as plot(). 

This is very annoying. So that I have to exit the server and re-login again. 

Does this sound familiar for you?

Here is the solution I found via website below:

http://b.kl3in.com/2012/01/x11-display-forwarding-fails-after-some-time/

Two ways to solve this:

1. add the following line to the Mac client’s /etc/ssh_config:

ForwardX11Timeout 596h
2. use “ssh -Y <remote system>”, instead of -X, as it may not trigger the untrusted auth timeout.